A device and a method for mode locking are specified in the document US 2006/187537 A1.
U.S. Pat. No. 5,077,815 relates to a device for optically connecting a single mode fiber to a multimode fiber.
A lightwave transmission system which uses selected optical modes is described in U.S. Pat. No. 5,416,862.
International Patent Publication WO 2008/135034 A1 relates to a wavelength-tunable laser.